1. Field of The Invention
The present invention relates to a process for producing an anti-blocking agent master batch, and more particularly, to a process for producing an anti-blocking agent master batch of a polyolefin-based resin providing film which has a good dispersion of polymer fine particles as an anti-blocking agent to a polyolefin-based resin, and is excellent in appearances such as transparency, see-through feeling, little generation of white spots (called as fish-eye) and the like, and in anti-blocking property.
2. Description of the Related Arts
A polyolefin-based resin film is used for materials for food packaging and textile packaging, and the like, because it is superior in physical properties such as transparency, mechanical property and the like.
However, the polyolefin-based resin in which an anti-blocking agent was added, has been used because the film made of the polyolefin-based resin not containing the anti-blocking agent has an insufficient anti-blocking property, piled films are mutually adhered, and the operability at packaging is lowered.
A polyolefin-based resin composition using polymer fine particles as an anti-blocking agent is reported. For example, polymer fine particles having a particle diameter of 3 to 40 xcexcm and no melting point in JP-A-57-64522, inert organic polymer crosslinked particles having a weight average particle diameter of 0.5 to 7 xcexcm in JP-A-05-214120, and a polyolefin-based resin composition using particles of a crosslinked polymer, as an anti-blocking agent, obtained by copolymerizing an acrylic monomer and a styrene monomer as main components which has a average particle diameter of 0.4 to 7 xcexcm and a film made of the composition in JP-A-06-107868, are reported.
Further, a method of using a raw material resin obtained by previously adding the requisite quantity of an anti-blocking agent to a polyolefin-based resin is usually used as a production process of a film.
However, this process requires a preparation of many raw material resins, in accordance with the kinds of films. Further, as the concentration of the anti-blocking agent is low, the raw material resin becomes a large volume, and the production efficiency of the film is lowered.
Therefore, in order to improve the production efficiency, there has been recently used a process which comprises preliminarily preparing a raw material resin having a high concentration of an anti-blocking agent, namely a master batch, and properly adjusting the concentration of the anti-blocking agent by diluting the master batch with a polyolefin-based resin thereby to produce a film.
However, although the dispersability of the polymer fine particles as the anti-blocking agent in the polyolefin-based resin was fairly improved compared to that of an inorganic anti-blocking agent such as silica fine particles, the that of the polymer fine particles as the anti-blocking agent in the polyolefin-based resin is not necessarily sufficient, and the master batch contained coagulated matters of the polymer fine particles as the anti-blocking agent in the polyolefin-based resin. When a film is produced by diluting the master batch with the polyolefin-based resin and forming into the film from the diluted resin, there were problems that the coagulated matters are not dispersed, white spots caused by the coagulated matters are generated, the appearance of the film is deteriorated, and points not inked to the film are generated at printing, etc. The above-described problems have been appeared in accordance with heightening of levels required in film properties.
Under these circumstances, the present inventors have intensively studied and as a result, found that the above-mentioned problems can be solved by using an anti-blocking agent master batch prepared by melt-kneading a polyolefin-based resin with polymer fine particles, as an anti-blocking agent, containing a specific quantity of a volatile component thereby to complete the present invention.
An object of the present invention is to provide an anti-blocking agent master batch being able to provide a polyolefin-based resin film which has a good dispersion of polymer fine particles as an anti-blocking agent in a polyolefin-based resin, and is good in appearances such as transparency, see-through feeling, little generation of white spot (occasionally called as fish eye) and the like, and in anti-blocking property and the like, and a polyolefin-based resin film made of the master batch.
Namely, the present invention relates to a process for producing an anti-blocking agent master batch, which comprises melt-kneading 100 parts by weight of a polyolefin-based resin (A) and 2 to 100 parts by weight of a polymer fine particles(B) containing 0.10 to 20% by weight of a volatile component as an anti-blocking agent and further, to a film made of the above-mentioned anti-blocking agent master batch.